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Finding the Carbon in Sugar

Author(s): Nancy P. Moreno, PhD, Barbara Z. Tharp, MS, and Judith Dresden, MS.

Let's Talk About It

In this activity, students observed an example of combustion: burning sugar. When placed over a flame, the sugar turned amber-colored, and then black.  

Ask students, What happened to the sugar? Help them to recognize that the sugar underwent a physical change (solid to liquid) and a chemical change (burning of liquid sugar). Ask, What do you think the black substance is? Help students to understand that the remaining material is mostly composed of carbon. Have students think about coal and crude oil.

Now ask them, Where did the carbon in the sugar come from? Lead students to understand that the carbon was drawn from air, as carbon dioxide, during photosynthesis in the leaves of plants. Have students examine the bottom of the spoon. Ask, Where did that carbon come from? Help them understand that that carbon comes from the burning of the candle wax.

Challenge students to think of other examples of combustion (e.g., burning wood, combustion of gasoline that runs a car engine). 

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education